Model Output Discussion 26/10 2012 >

[legritter]

Well good consistency from the GFS.

Even in FI, both the 00z and 06z are showing similar synoptics, big high to the east and a trough to the west with us pretty much in no mans land.

Certainly not mild, but not frigid cold either.yes a good run from GFS if you like to be kept on your toes . just need a few more like that with ECM becoming a bit more persistant .but if you like it normal ,the next 5/6 days should deliver . are we in for a change synoptic wise ,possibilitys but as usual more runs needed .

[Glacier Point]

Something 'interesting' for cold synopticians definately beginning to sir now in the extend range for final third of the month / start December.

We have various teleconnectors (principally a poleward migrating +AAM signal and coupled MJO wave) siganlling high latitide block at this time.

Last couple of GFS runs from around mid month onwards starting to hint at split vortex scenario. This includes a split lower stratospheric vortex programmed with lobes centred over Siberia and Canada.

Last 3 CFS runs for weeks 3 and 4 have developed blocking structures over Greenland / Iceland locale, and today forecast is for cross polar ridge.

http://origin.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk3.wk4_20121104.z500.gif

(note the Kamchatkan ridge / Greenland ridge wavelength there)

I suspect that this is a failry strong signal if both teleconnectors and modelling is consistently picking this.

Edited November 5, 2012 by Glacier Point

[Nick F]

With a large blocking high over E/NE Europe and W Russia, there looks like there will be little change in the upper wave pattern - i.e. mean trough staying just to our west and mean ridge staying put to our east. Unfortunately for those wishing for drier and more settled conditions, the high is a looking to be little too far east atm to prevent Atlantic frontal systems from moving across the UK.

Edited November 5, 2012 by Nick F

[legritter]

I completely cocked up on last post ,Post 644 ,Mixing up on multi quote etc ,my apologes

[Timmytour]

I completely cocked up on last post ,Post 644 ,Mixing up on multi quote etc ,my apologes

It was a bit confusing to read....but you could have gone back and edited it? :-)

To my highly untrained eye, I like the way the GFS shows an increasing difficulty for Atlantic lows to push through from west to east especially after next weekend. it does seem like an invitation is being extended from the UK to the east to come and take over.

[MR EXTREMES]

Trouble is blocking not as robust as 2010 and its very possible that we could be suck in the middle like last winter although south tracking jet and low heights in Europe may keep heights to our North held.

Although last winter was cold in Europe but we missed out.

Another blank sun would help but enso is on our side slight el Nino high hurricaine season could play in favour to.

Would love to see major nao dip and ao dip like 2010 add good ssw event then bingo still time yet though.

[Frosty.]

The latest ens mean from the gfs and ecm shows a limpet low through FI just to the west or northwest of the uk with a large high in the western atlantic and a huge anticyclonic block covering russia and eastern europe, the uk is locked into an unsettled spell which persists beyond mid month, the gfs mean has even backed off from the more benign pattern it was showing yesterday from around mid month onwards, now it's just unsettled with a showery W'ly flow and temps of around 8-10c. This week will turn a little milder but also cloudier with some rain and drier, brighter spells as winds start to blow in from the atlantic rather than polar regions, by tomorrow nearer 8-10c, up on today's 6-8c, so tonight's slight frost in the south will probably be the last until later in the weekend, by midweek through to friday the temps nearer 10-12c, maybe a 13c near the south coast and southeast but by saturday it looks cooler and more unsettled again as a trough drifts down from iceland and then this trough cannot really go anywhere next week due to blocking in the western atlantic and far eastern europe/russia.

Edited November 5, 2012 by Frosty039

[EML Network]

Well I don't know about everyone else, but the next week at least looks very drab, neither one thing or another, UK seems to be stuck in no mans land, not the most interesting of weeks no matter what your preference.

Looking further ahead and things don't really look like changing very much...I hate it when we get stuck in a rut like this, about the only thing that might be of any interest this month is the possibility of some quite windy weather at times...I'm sure someone will find something of interest, but from where I'm sitting it looks like a pretty typical last month of autumn (for the UK) with not much going on.

This is why I really detest Novembers, of all the months in the year they are the most boring for weather in the UK ...on a par with May

[johnholmes]

You have already forgotten the latter third of 2010! A once in a lifetime happening perhaps that many of us experienced just 2 years ago. I still remember that and especially the 35cm of snow starting about 5pm on the 30th after a week of cold and some snow the snow finally stopped some 15 hours later.

[legritter]

It was a bit confusing to read....but you could have gone back and edited it? :-)

To my highly untrained eye, I like the way the GFS shows an increasing difficulty for Atlantic lows to push through from west to east especially after next weekend. it does seem like an invitation is being extended from the UK to the east to come and take over.

I will try again ,still learning at 60yrs ,Yes looking at charts today i hope the invitation to the beast is taken up , but IF it comes off it could be a slow process .

[johnholmes]

To return to the models.

Unusually I have spent about 1 hour scouring as many outputs as I can from the usual 3 into others, synoptic type, ensemble types, from T=120 out to T+384 on some, looking at further out teleconnections that may affect things out as far as T+384. I can honestly say that unless my experience is letting me down very badly, both on this forum and prior to that, then I can only see a movement at the surface and in the upper air that suggests west to east with no indication to me in this time scale of anything starting to shift in the opposite direction. If that does begin to show then it is highly unlikely to be anything of any consequence before late November in my view. Others may of course disagree which is fine but I honestly cannot see the major high over Russia migrating west sufficiently to affect us. Its presence has to be a reaonably good thing fior cold lovers as it is quite likely a consequence of the developing snow cover in that area.

If we are to get a cold blast then it would seem it will occur from a direction north of west, possibly if all things work in unison a direct northerly?

Anyway that's my twopence for what it's worth this evening.

[phil nw.]

Today,s outputs show the UK remains pretty much in a Westerly Atlantic pattern for the next 10 days at least.

The 12z GFS/UKMO charts agree on a succession of the troughs and ridges moving across in a somewhat less colder flow than recently.

Here at T144hrs we can see this pattern.

Evidence of building heights further east again showing but really too far away to be of any influence other than to lock in the mean upper trough around or just to the west of the UK for the foreseeable.

I wouldn`t dismiss Russian heights completely and those height anomolies are forecasted to be present into week 2 by both the NAEF`s and ECM mean heights.These will need to be monitored as they may become more noticable later in the month.

Much depends on whether the hemisphere`s flow continues to buckle if not then all we may well get is an amount of mid-latitude blocking.

The main point for now is while we have a chunk of the vortex around Greenland spilling south and east towards the UK- as currently modelled- there is too much forcing to allow anything from the east to come this way.

Edited November 5, 2012 by phil n.warks.

[johnholmes]

Its interesting playing the NAEFS anomaly charts through right out to T+384 in that they show no hint of an upper ridge to the east moving west. Just how reliable this model is I have no idea. How about someone volunteers to do a check on it out, say, T+240, much as I do with the 3 anomaly charts to see how reliable it is?

Now there is a request one of you must find too good not to take up. It would be another help in trying to unravel weather predictions beyond T+120/144!

[IDO]

I agree with Mr Holmes' post. In fact the more I look at the charts the more I see the possibility that a Bartlett High is just as likely as a Scandi High block. The zonal setup bringing low after low from the west, halting on occasion, when the Scandi High tries to build, but the lows eventually push through again. At lower latitudes HP after HP co-join to reinforce the MLB and if that Scandi high sinks then we may have a zonal flow for sometime, especially with the forecast and prevalent continued cooling of the stratosphere.

T384 on GFS 12z:

h500slp.png

Not a pretty picture as we head towards December.

[bluearmy]

looking through the gefs members for 20th november and there arent many that resemble what the NH should look like at this juncture of the season. looking at the mean would indicate that the naefs anomolys will begin to push west on this evenings output. how much depends on how keen the gem ens are building the scandi block. noaa cpc should be a good indicator today with forecaster input following the weekends automatic naefs represenatation.

[Frosty.]

T384 on GFS 12z:

h500slp.png

Not a pretty picture as we head towards December.

Nothing is set in stone, the next few weeks look generally unsettled with a flow mostly from a westerly point but beyond that is up for grabs, read GP's post No 645 to find a different view on late nov onwards....interesting cold synoptics evolving....

[phil nw.]

looking through the gefs members for 20th november and there arent many that resemble what the NH should look like at this juncture of the season. looking at the mean would indicate that the naefs anomolys will begin to push west on this evenings output. how much depends on how keen the gem ens are building the scandi block. noaa cpc should be a good indicator today with forecaster input following the weekends automatic naefs represenatation.

Yes seen them Nick.Still the trend to keep a disorganised PV so maintaining interest in a pattern change before month end.

[SMU]

Evening All-

Calling it as i see it- a pretty poor days modelling if your looking for Cold-

The scandi block whilst developing is being modelled to be shunted away & its not until 240 that the ECM starts to get traction Northwards towards Svalbard-

I still think the models are being very fast- so we will see what tomorrow brings-

One thing of note is the Cooling in the stratosphere is being modelled to have an impact around 60N - however how long will it sustain for-

Perhaps our real test of the decent autumn synoptics coming up-

Cheers

Steve

[Frosty.]

The Gfs 12z op run shows a cooler weekend following the milder blip with temps back to 7-8c and 0-1c overnight although saturday night would be a little milder in the southeast corner so frost free there, but a widespread frost for northern and western areas and by sunday night a frost just about anywhere, sub zero in rural areas as a flat ridge topples east through the weekend. Next week looks like becoming very unsettled after the brief respite and milder by monday but then there are frequent changes between milder and cooler for the rest of the run, the middle of next week looks particularly wet and windy with S'ly gales but then the low tends to fill slowly but remains slow moving before further atlantic lows begin to push east, the anticyclonic block to the east looks like slowing down or even stalling the lows over the uk so we could be looking at local flooding next week.

[johnholmes]

An interesting peek at the accuracy of 500mb synoptic charts across the northern hemisphere is that ALL the models have shown below their own average results since the start of November.

Steve did post the Euro zone link but as usual I've lost it so no idea if this is true for that specific area as well?

[Gibby]

Good evening. Here is my take on the 12zs from GFS, UKMO, GEM and ECM for today Monday November 5th 2012.

All models are fairly united on events for the weather over the UK over the rest of the working week. A ridge of High pressure is currently covering the UK with a cold frosty night likely for many. Tomorrow will see winds back towards the NW or West with cloudier and milder air filtering across the UK during tomorrow. The weak warm front in the flow may well give some light rain and drizzle at some point tomorrow. Wednesday and Thursday look broadly similar with a fresh breeze and a lot of cloud continuing with some light rain at times, especially for a time on Thursday. Brighter skies follow a weak cold front East on Thursday to give a cooler night on Thursday and a bright start to Friday before a Low pressure trough inches in towards the North and West late in the day bringing the risk of rain later.

GFS then shows the weekend starting wet as a cold front crosses East carrying a band of more noticeable rainfall and followed by clearer and colder weather behind. Sunday sees a ridge following with a colder and drier day for all in a light wind before an increase in winds from the SW brings a return to milder weather and rainfall to the NW on Monday. As we go through the working week a vigorous Low pressure is shown moving across the UK with wind and gales likely towards midweek followed by colder and more showery conditions later on . Later into FI the changeable theme continues with a trend to drier and brighter conditions for the South late in the run.

The GFS Ensembles show a pretty flat pattern over the coming two weeks as 850's average very close to normal. Rainfall increases for most after the drier interlude of this.

The Jet Stream flow shows the main arm to affect the UK undulating across the Atlantic and over the UK in the coming week or so.

UKMO for noon on shows a broad West or SW flow over the UK with the weakest of ridges crossing the UK ahead of a warm front later. After a bright and breezy start a change to cloudy weather with rain will move East or NE over the UK on Sunday night.

GEM shows a cold front crossing East over the weekend with rain followed by colder air and a few showers in brighter conditions later. It will be windy over the weekend.

ECM too shows an increasingly unsettled end to it's run under a similar deep Low pressure area centred to the NW carrying wind and rain NE across all areas at times in relatively mild conditions.

In Summary there is a strong signal for a period of unsettled and changeable conditions across the UK for the coming few weeks. Temperatures will end up at respectable levels generally with any colder incursions very temporary or non existent. It will be windy at times with SW gales possible at times, especially in the North and West. With all Northern blocking removed from much of the output on our side of the Northern hemisphere it looks like this pattern of Low to the NW and Higher pressure to the South or East could last a while.

[liam300]

What an awful day for the models, although this has coming for the last few days with not a lot of positive reports.

Im not one to rule out the winter altogether, although this doesn't look look for the future with the Nothern blocking being removed.

[Frosty.]

Yes I think we need to continue looking west and even briefly south at times for the next 2-3 weeks rather than east or north, the anticyclonic block is much further away than on some of yesterday's modelling and the only impact it would have is stalling depressions right over the uk for long periods, we are the sandwich filling with low pressure over our part of the world and high pressure which will be covering the western side of the atlantic and that russian high which is a monster.

Edited November 5, 2012 by Frosty039

[cold snap]

if one could clutch a straw ecm at 240 isnt the worse chart in the world does have some interest that the pattern may change .theres always cfs for the serious straw clutcher.no deep cold into europe thats the big issue.

Edited November 5, 2012 by cold snap

[EML Network]

You have already forgotten the latter third of 2010! A once in a lifetime happening perhaps that many of us experienced just 2 years ago. I still remember that and especially the 35cm of snow starting about 5pm on the 30th after a week of cold and some snow the snow finally stopped some 15 hours later.

Yeah I'll give you that one, November 2010 was as exception , especially the last 5 days of it :-)